[Coco] FPGA CoCo

[jdaggett at gate.net]

On 27 Mar 2006 at 0:06, Gene Heskett wrote:

> This is beginning to sound rather appetizing James.  Do keep us posted,
> and see if you can come up with a cost for the finished version.  Then
> another question sticks up its hand and waves for attention, & that is:
> Are you going to do an interface that will let us use our current
> cartridges, disk, seriel etc cards as we now use them in the multipack. 
> Or is that so far down the road its not a visible object yet?

******

Right now things are being done in a XC2S300E FPGA(Spartan2e). IF I were to to 
go to production it will end up in a Spartan3. Most likely an XC3S400. That part is 
half the cost of the part I am using now. 

Like Mark stated with his project, Basically this is just beyond the feasability stage. 
The problem making hardware backward compatible is that the 40 pin card 
connector used in the Cocos are obsolete and as rare as hen's teeth. The only 
source that I can see fo rthese connectors is old dead Coco mobos or MPI. I 
imagine a modified ISA connector could be used.

That is where the rub comes in. Doing an FPGA with CPU, GIME+, PIA chips and 
other circuitry in one FPGA makes it rather difficult to be backward compatible 
hardware wise. Just doing a GIME+ chip and shoe horn it into a current Coco 3 is 
somewhat doable. But whether it is cost effective is another item. 

As the weather heats  up this summer here is Central Florida,  I will have the 
afternoons to work on this project more. Right now thrying to accomplish all the 
outside work around the house that my father and I can while the daytime temp 
stays below 90F/32C.

james